US prosecutors have arrested four men accused of being Venezuelan agents involved in attempts to smuggle cash to an Argentine politician.
President Chavez publicly endorsed Mrs Kirchner's campaign
Miami prosecutors accuse the men of conspiring to conceal the source of $800,000 (£392,000) carried into Argentina in a suitcase.
They have reportedly said the money was meant for the campaign of Argentina's newly elected president.
The charges have drawn a strong rebuke from Venezuela.
The criminal complaint against the four men - three Venezuelans and a Uruguayan - said that "neither the true source nor the intended recipient of those cash funds had been disclosed".
But Assistant US Attorney Thomas Mulvihill said on Wednesday that an FBI recording showed that the money was destined for the campaign of new Argentine President Cristina Fernandez de Kirchner, the Associated Press news agency reported.
Mrs Kirchner was elected in October.
A presidential spokesman in Buenos Aires said Mrs Fernandez's office had no information about the charges and would look into the case before responding, according to AP.
Prosecutors say the defendants were undeclared agents and held meetings in Florida with a Venezuelan-American businessman, Guido Antonini Wilson, in an attempt to pressure him to hide the source of the money and its destination.
Mr Antonini Wilson was part of a delegation flown in to Buenos Aires by the Argentine government on a private jet in August.
Customs officials discovered $800,000 in undeclared cash in his suitcase, and issued an extradition warrant when he fled to the US.
The businessman is not accused of any crime by the American prosecutors.
Venezuelan Foreign Minister Nicolas Maduro called the charges "a desperate effort by the United States government using... the judicial branch for a political, psychological, media war against the progressive governments of the continent".